Microbiology Lecture 2.

Question 1

Pediculus humanus capitis: site, classic presentation, treatment

Answer 1

head lice - scalp esp behind ears; schoolgirls sharing hair accessories/winter coats; treatment = nit combing, topical insecticide, hot-wash all clothing and linens

Question 2

Pediculus humanus capitis special consideration

Answer 2

allergic reactions to louse saliva, secondary staph infection

Question 3

Pediculus humanus corporis: site, classic presentation, treatment

Answer 3

clothing, esp seams; shows on homeless; treatment = refer for services/improve hygiene, discard clothing

Question 4

Special consideration for pediculus human corporis

Answer 4

can transmit typhus, trench fever, relapsing fever

Question 5

Pthirus pubis: site, classic presentation, treatment

Answer 5

pubic hair, shows up in sluts, treatment: hot-wash all clothing, linens, shave your pubes

Question 6

How can pedicures humans capitis and corporis be distinguished by pthirus pubis on microscopy?

Answer 6

capitis and corporis are elongated, pubis is are wide like crabs

Question 7

Bacteriology of treponema pallidum

Answer 7

“corkscrew” motion, not culturable, slow growing, too slender for gram stain, too delicate to survive outside host

Question 8

How is treponema pallidum viewed?

Answer 8

too small for standard microscopy, need dark field (no gram stain)

Question 9

How does treponema pallidum transmit?

Answer 9

sexually (low infectious dose), transplacental, blood-blood

Question 10

How does treponema pallidum infect after it is transmitted?

Answer 10

penetrates mucous membranes or small abrasions - then grows in blood vessel endothelium, enters blood and lymphatics

Question 11

Primary syphilis

Answer 11

weeks: initial replication at site of infection, forms an ulcer, initiates bacteremia (heals in 3-12 weeks)

Question 12

Secondary syphilis

Answer 12

months: 4-10 weeks: macropapular rash on palms and soles, moist papules on skin and mucous membranes, high infections moist lesions on genitals “condylomata lata” (come together), low fever, malaise, anorexia, weight loss, headache, myalgia, lymphadenopathy

Question 13

What happens after secondary syphilis?

Answer 13

1/3 resolve, 1/3 enter latency (years) - early latency symptoms come and go, patient remains infections, late latency symptoms absent and not infection, 1/3 enter tertiary syphilis

Question 14

Does the host raise antibodies to treponema pallidum?

Answer 14

yes but immunity is noncompete because surface of spirochete is nonimmunogenic and down regulates TH1 cells making antibodies useless

Question 15

Tertiary syphilis

Answer 15

destructive stage: granulomas, CNS involvement - early meningitis, late neurosyphilis - meningovascular syphilis (popping blood vessels in brain), parenchymal neurosyphilis (tabes dorsalis and general paresis)

Question 16

congenital syphilis

Answer 16

spirochetes easily cross placenta and survivors (50% die before birth) develop severe secondary syphilis and physical abnormalities

Question 17

What is the relationship between treponema and HIV?

Answer 17

treponema facilitates HIV infection because ulcerations and HIV immunosuppression accelerates treponema course and reduces efficacy of treatment

Question 18

What is the tell-tale sign of treponema infection?

Answer 18

Argyll-Robertson pupil: one or both pupils fails to constrict in response to light, but behave normally in accommodation (able to constrict on near object)

Question 19

Why is diagnosing treponema difficult?

Answer 19

the “great imitator” - history is difficult because it can extend over years with varied symptoms developing and resolving

Question 20

What lab work can be done to diagnose treponema?

Answer 20

microscopy: swab lesions for darkfield microscopy or IF, biopsy gummas for histology with silver or IF serology: reagin - nonspecific antibodies can be detected with cardiolipin (VDRL or RPR); specific antibodies detectable by IF or hemagglutination; NAAT

Question 21

What is the treatment for treponema?

Answer 21

penicillin g! allergy = long-term doxycycline, erythromycin, ceftriaxone

Question 22

How do you know treatment for treponema was effective?

Answer 22

Jarisch-Herxheimer reaction (flu like symptoms after 24h)

Question 23

What will have RPR and VDRL + test results similar to treponema pallidum (syphilis)

Answer 23

treponema pertenue (yaws) and treponema carteum (pinta)

Question 24

What is yaws and how is it treated?

Answer 24

treponema pertenue - tropical disease of overcrowding and poor sanitation - spread by DIRECT contact - three phases like syphilis but no neuro-cardio involvement - treat with penicillin

Question 25

What is pinta and how is it treated?

Answer 25

treponema carateum - central and south america, no constitutional symptoms - hypo and hyper-pigmented skin plaques - spread by DIRECT contact - treat with penicillin